A photosensitive flexographic resin plate is usually prepared from a composition containing a resin having rubber elasticity, an addition-polymerizable unsaturated monomer and a photopolymerization initiator. The photosensitive flexographic resin plate, when cured, is required to have a suitable hardness (JIS A Hardness: 30.degree. to 80.degree.) and impact resilience of more than 20%.
In many cases, the requirement is satisfied by adding a softening agent or plasticizer. However, the addition of such an agent adversely affects mechanical strength to result in the crack of the printing plate and the imperfection of relief image. The printing plate containing a softening agent or plasticizer, therefore, is not good for industrial usage and is only for a limited usage.
In order to improve the above-mentioned defect, it is proposed to add a filler, such as silica, extender, glass fiber and the like. However, since the filler is different from a base resin in refractive index, particle distribution, composition and the like, it adversely affects the duplicativity of relief image because of the dispersion of irradiated light.